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In situ stress variations near faults considering fault zone rock rheology - implications for reservoir stimulation and associated seismicity

Applicant Ma Xiaodong
Number 182150
Funding scheme Project funding (Div. I-III)
Research institution Departement Erdwissenschaften ETH Zürich
Institution of higher education ETH Zurich - ETHZ
Main discipline Other disciplines of Earth Sciences
Start/End 01.02.2019 - 31.01.2023
Approved amount 281'964.00
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All Disciplines (3)

Discipline
Other disciplines of Earth Sciences
Geology
Geophysics

Keywords (4)

reservoir stimulation; in situ stress; fault; seismicity

Lay Summary (German)

Lead
in situ belasteten räumlichen Variationen in der Nähe der Störungszone vom Fernfeld bis zur Schadenszone und zum Störungskern
Lay summary

Das Projekt sucht nach einem besseren Verständnis der in situ belasteten räumlichen Variationen in der Nähe der Störungszone vom Fernfeld bis zur Schadenszone und zum Störungskern. Die Forschung wird im Zusammenhang mit der Verbesserung der hydraulischen Stimulation und Milderung der Seismizität in Reservoiren für geothermische Systeme (und / oder Kohlenwasserstoffe, Abfallentsorgung) durchgeführt, da Störungen sowohl als Flüssigkeitsleitungen als auch als Erdbebenquellen dienen. Dieses Projekt ist eng mit den Feldversuchen des Schweizerischen Kompetenzzentrums für Energieforschung - Stromversorgung (SCCER-SoE) im geplanten U-Bahn-Labor Bedretto, Schweizer Zentralalpen verbunden. Dies ist ein wichtiger Schritt, um die Schweizer Energiestrategie bis 2050 für 7% tiefe Geothermie (aus heißem trockenem Gestein) anzugehen. In erster Linie bemüht sich das Projekt unter anderem um folgende Herausforderungen:

• Inwiefern unterscheiden sich die in situ Spannungen innerhalb und innerhalb der Störungszone?

• Inwieweit verursachen Lithologie- und Fehlerstrukturvariationen Spannungsänderungen?

• Können wir die räumlichen / zeitlichen Spannungsschwankungen angesichts des Fernfeldspannungszustands und der Fehlerstruktur vorhersagen?

Um diese Herausforderungen zu lösen, wird eine integrierte Geomechanik-Studie über kombinierte Feld-, Labor- und theoretische Ansätze erstellt. Insbesondere wird die Studie mit einer Feldkomponente beginnen, um den in situ Spannungszustand (und seine Variationen) in der Nähe der Störungen zu charakterisieren, die das Bedretto Underground Laboratory (BUL) durchschneiden. Die in situ gemessenen Spannungsschwankungen und die charakterisierten Fehlerstrukturen werden korreliert, um eine plausible kausale Beziehung zu identifizieren. Daraufhin werden Versuche unternommen, um die wahrscheinlichen Spannungsschwankungen um die Fehler zu extrapolieren, basierend auf der vom Labor abgeleiteten Beziehung. Die vorhergesagten Spannungsschwankungen werden mit den In-Situ-Messungen verglichen.

Direct link to Lay Summary Last update: 07.03.2019

Lay Summary (English)

Lead
In situ stress variations near faults considering fault zone rock rheology - implications for reservoir stimulation and associated seismicity
Lay summary

The project seeks a better understanding of the in situ stress spatial variations near fault zone from the far-field, to the damage zone and to the fault core. The research is conducted in the context of improving hydraulic stimulation and mitigating seismicity in reservoirs for geothermal systems (and/or hydrocarbons, waste disposal), as faults act as both fluid conduits and earthquake sources. This project is closely associated with the field experiments of the Swiss Competence Center for Energy Research – Supply of Electricity (SCCER-SoE) in the planned Bedretto Underground Laboratory, Swiss Central Alps. which serves as a key step to address the Swiss Energy Strategy by 2050 for 7% deep geothermal energy (from hot dry rocks). Primarily, the project strives to tackle the following challenges (among others):

  • To what extent do the in situ stresses vary approaching, and within, the fault zone?
  • To what extent do lithology and fault structure variations induce stress changes?
  • Can we predict the spatial/temporal stress variations, given the far-field stress state and fault structure?

An integrated geomechanics study via the combined field, laboratory and theoretical approaches will be established to resolve these challenges. Specifically, the study will begin with a field component to characterize the in situ stress state (and its variations) near the faults intersecting the Bedretto Underground Laboratory (BUL). The measured in situ stress variations and the characterized fault structures will be correlated to identify a plausible causal relationshipThis is followed by attempts to extrapolate the likely stress variations around the faults, based on the laboratory-derived relationship. The predicted stress variations will be compared with the in situ measurements.

Direct link to Lay Summary Last update: 07.03.2019

Responsible applicant and co-applicants

Employees

Project partner

Publications

Publication
Hydraulic stimulation and fluid circulation experiments in underground laboratories: Stepping up the scale towards engineered geothermal systems
Gischig Valentin S., Giardini Domenico, Amann Florian, Hertrich Marian, Krietsch Hannes, Loew Simon, Maurer Hansruedi, Villiger Linus, Wiemer Stefan, Bethmann Falko, Brixel Bernard, Doetsch Joseph, Doonechaly Nima Gholizadeh, Driesner Thomas, Dutler Nathan, Evans Keith F., Jalali Mohammadreza, Jordan David, Kittilä Anniina, Ma Xiaodong, Meier Peter, Nejati Morteza, Obermann Anne, Plenkers Katrin, et al. (2020), Hydraulic stimulation and fluid circulation experiments in underground laboratories: Stepping up the scale towards engineered geothermal systems, in Geomechanics for Energy and the Environment, 24, 100175-100175.
Coulomb criterion - bounding crustal stress limit and intact rock failure: Perspectives
Ma Xiaodong, Saar Martin O., Fan Liang-Shih (2020), Coulomb criterion - bounding crustal stress limit and intact rock failure: Perspectives, in Powder Technology, 374, 106-110.
Global Frictional Equilibrium via Stochastic, Local Coulomb Frictional Slips
Zhang Shihuai, Ma Xiaodong (2020), Global Frictional Equilibrium via Stochastic, Local Coulomb Frictional Slips, in Earth and Space Science Open Archive , NA.
Preliminary in situ stress and fracture characterization in the Bedretto Underground Laboratory, Swiss Alps: Implications on hydraulic stimulation
MaXiaodong, DoonechalyNima, HertrichMarian, GischigValentin, KleeGerd (2019), Preliminary in situ stress and fracture characterization in the Bedretto Underground Laboratory, Swiss Alps: Implications on hydraulic stimulation, in Rock Mechanics for Natural Resources and Infrastructure Development, CRC Press, London.

Associated projects

Number Title Start Funding scheme
189632 Monitoring and scientific equipment for the Bedretto Deep Underground Laboratory for Geoenergies 01.12.2019 R'EQUIP

Abstract

The proposed project is seeking for a better understanding of the in situ stress spatial variations near faults, in the context of improving hydraulic stimulation and mitigating seismicity in reservoirs for geothermal systems (and/or hydrocarbons, waste disposal), as faults act as both fluid conduits and earthquake sources. This project is closely associated with the field experiments of the SCCER-SoE in the planned Bedretto Underground Laboratory, which serves as a key step to address the Swiss Energy Strategy by 2050 for 7% geothermal energy. Primarily, the project strives to tackle the following challenges (among others):1To what extent do the in situ stresses rotate and vary approaching, and within, the fault zone? Are stress variations scale-invariant? (field aspect)2To what extent do lithology and fault structure variations induce stress changes? Is visco-plastic stress relaxation or elasticity contrast the main cause for stress variations, or could it be something else? (laboratory aspect)3Can we predict the spatial (and temporal) stress variations, given the knowledge of the far-field stress state and fault structure? Accordingly, how can the knowledge on stress variations improve the 'steering' of hydraulic fracturing/shearing and mitigate seismicity? (theoretical and computational aspects)An integrated geomechanics study via multi-disciplinary approaches will be established to resolve these challenges. Funding to sponsor one PhD student is sought to carry out the study. Specifically, the study will begin with a field component to characterize the in situ stress state (and its variations) near the faults intersecting the Bedretto Underground Laboratory (BUL). This will proceed in accordance with the field geologic characterization by the SCCER-SoE at BUL. The measured in situ stress variations and the characterized fault structures will be correlated to identify a plausible causal relationship. Then, rock mechanical (elastic, visco-plastic) properties of the extracted fault zone rock samples will be characterized in the laboratory to establish a rigorous constitutive relationship and to quantify the effects of lithology and damage on rock rheology. This is followed by attempts to extrapolate the likely stress variations around the faults, based on the laboratory-derived relationship. The predicted stress variations will be compared with the in situ measurements, and the effects of stress variations on the effectiveness of stimulation and associated seismicity will be examined under different scenarios of stimulation strategies employed in the BUL field experiments.The project outcomes will bridge field observations and laboratory characterizations of reservoir-scale faults, representing a new level of understanding of the in situ stress field and its variations. Strong collaboration within the SCCER-SoE will advance the research on reservoir stimulation and seismicity mitigation. Furthermore, the laboratory/field workflow and the produced datasets by themselves are valuable because of the relative scarcity of relevant studies.
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